Table 4.

Genes of Interest in the Differential Diagnosis of Early-Onset or Severe Molybdenum Cofactor Deficiency

Gene(s)DisorderMOIClinicoradiographic FindingsLaboratory Findings / Comment
SUOX Isolated sulfite oxidase deficiency (ISOD)ARIdentical to MoCD
  • ↑ plasma taurine
  • ↑ urinary thiosulfate & S-sulfocysteine
  • ↓↓ plasma levels of total homocysteine & cystine
Unlike MoCD, serum uric acid levels are normal in ISOD ‒ as are urine xanthine & hypoxanthine levels.
ALDH7A1 Pyridoxine-dependent epilepsy (PDE)AR
  • Neonates w/pyridoxine-responsive seizures refractory to ASM & encephalopathy
  • Thinning of corpus callosum & mega cisterna magna on brain MRI
Unlike MoCD, PDE is not assoc w/widespread diffusion restriction on brain MRI.
  • ↑ alpha-aminoadipic semialdehyde in urine & plasma 1
  • ↑ pipecolic acid in urine & CSF
Unlike MoCD, sulfur metabolite labs are normal in PDE.
PNPO Pyridoxal phosphate-responsive epilepsy (See PNPO Deficiency.)ARNeonates w/pyridoxal-5' phosphate-responsive seizures refractory to ASM & encephalopathy
  • ↑ plasma lactate
  • Hypoglycemia
  • Normal to ↑ plasma glycine
  • Normal to ↑ plasma threonine
  • ↓ plasma arginine
PLPBP
(PROSC)		Early-onset vitamin B6-dependent epilepsy (See PLPBP Deficiency.)ARNeonates w/pyridoxine-responsive seizures refractory to ASM & encephalopathy
  • ↑ plasma lactate
  • Metabolic acidosis

AD = autosomal dominant; AR = autosomal recessive; ASM = anti-seizure medication; ID = intellectual disability; MoCD = molybdenum cofactor deficiency; MOI = mode of inheritance; XL = X-linked

1.

It should be noted that alpha-aminoadipic semialdehyde excretion has been detected in some individuals with molybdenum cofactor deficiency and isolated sulfite oxidase deficiency [Mills et al 2012, Struys et al 2012].

From: Molybdenum Cofactor Deficiency

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